Angela Merkel won. But how long can Germany's center hold?

Before it even went down on Sunday, Germany's elections were branded as "boring." And indeed, the headline result has been predictably boring: As was widely expected and forecast for months, Angela Merkel held on to her job as chancellor of Germany for a fourth term, riding a still-strong economy to overcome the unpopularity of her decision to open Germany's doors to migrants from the Middle East and Africa. But look below the headline result and things are much less boring. Like the U.K.'s rece...